Load-bearing structures made of fiber composite materials exhibit advantageous strength to weight properties. A drawback of such structures is the relatively high production cost. These costs arise from the labour intensive and time consuming manufacturing process, which is associated with said structures.
The fibers of such composite structures, which fibers constitute the chief part of the load-bearing capability, are to be aligned in specific configuration in order to optimize the structures. Traditionally, this alignment has been made by winding the fibers around a mandrel or similar.
In modern manufacture, so-called prepreg has been used in order to speed the process up. Here, pre-impregnated mats of aligned fibers are used. The fiber mats can e.g. be impregnated in an epoxy resin, which resin thereafter is partially cured. The prepreg layers can manually or automatically, by means of a so-called tape layer, be applied onto a rigid or inflatable mandrel. Subsequently, the prepreg resin is cured by increasing the temperature and applying pressure. Generally, the pressure is applied by covering the layers with an outer membrane or by inflating the mandrel. A drawback of using an inflatable mandrel is that this procedure requires an outer female mould, which defines the outer shape of the product to be produced. On the other hand, a drawback associated with rigid mandrels is that the composite layers have a tendency to wrinkle under the applied pressure. Further, in known manufacturing methods, it is difficult to automatically, i.e. with a tape layer, accurately lay the prepreg layers up on the mandrel.